Conversion of cellulose into levulinic acid under the catalysis of Brønsted acidic ionic liquid and erbium chloride in water.

We propose a new approach for the synergistically catalytic conversion of cellulose to levulinic acid (LA) in water by SO3H-functionalized ionic liquid (SFIL) and lanthanide chloride (LnCl3). Compared with using 1-methyl-3-(3-sulfopropyl)imidazolium chloride ([MIMPS]Cl) only, the LA yield using [MIMPS]Cl and ErCl3 increased by 14.4% and 13.6% at 50 mol% of IL and 30 mol% of IL, respectively. Moreover, the combined [MIMPS]Cl and ErCl3 system can tolerate high concentrations of substrates and maintain high activity at eleven runs. We also investigated the effects of the cation structure of ionic liquids (alkyl chain length, hydroxyl groups on the side chains, and aromatic properties) on LA production. The observations can provide useful information for designing efficient ionic liquid catalysts for biomass utilization.